History

In its earliest incarnation, F Branch was responsible for preventive intelligence in the MI5 organisation of 1916.[1]

A new F Division covering counter-subversion was established by Director General Sir David Petrie in 1941.[2]

Counter-subversion branch

In Dick White's 1953 re-organisation, F Branch had responsibility for counter-subversion at home, while E Branch was responsible for counter-subversion in the British Empire and Commonwealth.[3]

In 1972, F Branch director John Jones defined subversion as "activities threatening the safety or well-being of the State and intended to undermine of overthrow Parliamentary democracy by political, industrial or violent means."[4]

The Prime Minister and Home Secretary had left him in no doubt that they wanted a major increase in effort on this target. He then handed over to a young and ambitious F Branch officer, David Ransome, who outlined the activities and structure of a host of left-wing splinter groups , like the Workers Revolutionary Party (WRP) and the Socialist Workers' Party (SWP).[5]

Stephen Dorril states that Ranson was an F2 officer at the time of this meeting, which he places in 1972.[6]

In 1976, Director General Michael Hanley established a separate FX branch to deal with Irish terrorism. Its director continued to report to the director of F Branch.[7]

By the time former F Branch director John Jones became head of MI5 in 1981, it had become the premier branch of the service, largely at the expense of K Branch counter-espionage.[8]

Workers Revolutionary Party

John's Lennon reportedly became an MI5 target after a mole reported his contacts with the party in the early 70s.[15]

Stephen Dorril suggests that MI5 may have been involved in a raid on the WRP's 'Red House' in the mid-1970s, and in promoting a split in the party in 1985-86. Ken Livingstone claimed in March 1990 that a high-ranking agent in the leadership had fomented the split.[16]

International Marxist Group

Militant Tendency

The Militant Tendency operated a covert Trotskyist grouping in the Labour Party in the 1970s. By the late 1970s, MI5 believed it had identified 75 per cent of its membership through various methods, including agent penetration.[18]

Trade Unions

TGWU

In October 1970, MI5 obtained a Home Office warrant against the general Secretary of the TGWU, Jack Jones, because of his contacts with the Russians. MI5 head Martin Furnival Jones noted that Jones was unlikely to be charged with espionage, but the operation "could be of great value in particular to the Department of Employment and to the Government generally in the field of industrial disputes.[19]

National Union of Mineworkers

According to Christopher Andrew, MI5 was unable to provide the Government with a full intelligence picture during the 1972 miner's strike, because its remit only extended to figures such as the Communist Scottish NUM leader Mick McGahey.[20]

On 14 November 1972, MI5 obtained a Home Office warrant against Arthur Scargill, "to help establish the extent of communist influence on present negotiations in the mining industry."[21]

Grunwick Dispute

The Guardian's Richard Norton-Taylor reports:

Elwell also targeted Harman's husband, Jack Dromey. He opened a file on him during the late 1970s after the Grunwick dispute, in which Dromey, now Labour party treasurer, played a leading part.[22]

According to former MI5 officer Cathy Massiter, whose desk dealt with CND, the problem was solved when, by chance, Mrs Ruddock was interviewed by a Soviet journalist, who was a KGB officer. "Joan Ruddock didn't know that, but it provided the grounds for recording her as a "contact of a hostile intelligence service."[26]

F1A

At one point, probably in the 1950s, this was the designation for the "study group" which identified Communist Party members, a traditional training ground for new MI5 officers.[41]
This section was tasked in 1975 to launch an wide-ranging investigation of subversion in the Labour Party.[42]

F1A/1 - noted in 1975 that work in this field was expanding to include the 'Ultra Left' where previously it had focused on Communists.[43]

F1A/9 - Wrote nine papers on Militant in the two years to January 1978.[44]

F1B

A full-time desk on Irish security issues, with a particular focus on the North, was set up in F1B in the spring of 1969. By the autumn of that year, F1B consisted of a female assistant officer supported by the young Stella Rimington.[45]

F1C

In the spring of 1969, an internal MI5 newsletter stated: "The total effort deployed by F. Branch in matters Irish was until recently confined to one part-time desk officer in F.1.C.[46] At some point F1C replaced F2C as the designation of the 'study group' section which identified Communist Party members.[47]

F2

Responsible during the early 1980s for investigating trade unions and the production of Box 500 reports, according to Stephen Dorril.[48]Responsible for investigating the Communist Party, according to Nick Fielding and Mark Hollingsworth. This may reflect a confusion with F1.[49]
According to Stephen Dorril, F2 worked closely with the Civil Contingencies Unit during strikes.[50]

F2A

F2C

Engaged in studies of the Communist Party, which were often used as training for new officers.[59] At some point it replaced F1A as the section designation for this activity. It was itself replaced by F1C.[60]

F6

F7

Investigated Trotskyist, anarchist, feminist, pacifist, black power, nationalist and other radical groups. Also fascists.[81]
Among the organisations infiltrated by F7 were the Workers Revolutionary Party and the Socialist Workers Party.[82]